Padrões de qualidade fisiológica e conservação de material propagativo de Handroanthus serratifolius (Vahl.) S.O.Grose

Abstract

Anthropic pressure on natural forests forces the creation of protocols to conduct reforestation, in addition to mechanisms for the conservation of species. Thus, the objective of this work was to demonstrate physiological quality standards for Handroanthus serratifolius seeds and to estimate pollen viability as an alternative for conservation. The study was carried out with 20 seed lots, collected from 20 matrices of the species. To characterize the matrices, DAP, commercial height, crown height and crown diameter were measured; and with the seed lots, the moisture content, weight of a thousand seeds, biometrics and germination characteristics were determined. From the collected data, an analysis of variance between lots was made, by variable in the Genes 6.1 software; a correlation matrix with the variables in RStudio 3.5.0 software; an analysis of the main components in the Past 4.02 software and; the repeatability coefficient was determined with the biometric variables in the Genes 6.1 software. To estimate the pollen potential, flowers were collected from five individuals and in different floral stages to estimate viable pollen by the colorimetric test with different dyes: Tetrazolium, Trypan blue and Cotton blue. The pollens were also submitted to germinative tests with two culture media, one control, based on agar and sucrose, and the other with added calcium; another three distinct genotypes were collected to find out the critical point for storage, where they were stored in a freezer at -20 ° C and evaluated (fresh, after 1 month, after 3 months and after 6 months), by colorimetric and germinative tests . For these tests, analyzes of variance between genotypes were made, using variables in the Rbio software. The matrices showed differences between them when compared and, thus, were divided into groups. The weight of a thousand seeds showed the greatest amplitude in the results. In the correlation matrix, the characteristics of the matrix tree did not influence the physiological potential of the seeds, however, the weight of a thousand seeds was strongly correlated with the biometric characteristics, and with the formation of seedlings. Germination (root emission) did not correlate with any variable worked; a fact similar to the response of the main components, where it demonstrated that the weight of a thousand seeds and the biometric characteristics were the variables that best explained the behavior of the population. The repeatability coefficient demonstrated that fourteen seeds are sufficient to characterize a batch. Regarding the pollen potential, both the dyes and the different floral stages did not present any differences, and in general the percentage of viable pollen varied in the range of 65 to 80%, for the different culture media, the addition of calcium showed a more satisfactory behavior when compared to the control medium, reaching 30% germination in some cases, but did not demonstrate the potential presented in the colorimetric tests. Regarding storage, pollens that were kept in a freezer lost their germinative power (pollen potential), but showed a high percentage of viable pollen by the colorimetric method ranging from 80 to 90%, with no differences between the periods of time.